Network device and operation method for network device

ABSTRACT

A network device in a network system including a plurality of network devices, includes: an identification unit to identify whether specific information is included in an uplink message received from a specific terminal device, where the specific information includes subscription-related information indicating that the specific terminal device has a subscription to a specific network device among the plurality of network devices and the specific terminal device is locally managed by the specific network device; a determination unit to determine whether to route the uplink message on the basis of the identification of the specific information; and a decision unit to decide the specific network device to which the uplink message is routed on the basis of the specific information when routing the uplink message is determined, where each network device of the network devices in the network system locally manages terminal devices which subscribes to each network device.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of International ApplicationNo. PCT/KR2017/006984 filed on Jun. 30, 2017, which is based on, andclaims priorities from, Korean Patent Application No. 10-2016-0125305,filed on Sep. 29, 2016, and Korean Patent Application No.10-2016-0128513, filed on Oct. 5, 2016. The disclosures of theabove-listed applications are hereby incorporated by reference herein intheir entirety.

FIELD

The present disclosure relates to an Internet of Things (IoT)technology. More particularly, the present disclosure relates to atechnology for improving performance of an IoT service by implementing acall processing scheme which is suitable for an IoT network and supportmobility of an IoT terminal.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and do not constitute prior art.

Internet of Things (IoT) technology for sharing information throughwired/wireless network connection between general objects has appearedand has been spotlighted in various fields such as health care, remotemeter reading, smart homes, smart cars, and smart farms.

An IoT network structure for providing an IoT service based on the IoTtechnology will be briefly described below.

The IoT network consists of a remote IoT terminal, a customer terminalconfigured to have an application for IoT (hereinafter, referred to asan IoT app) installed therein to identify data of the remote IoTterminal control the IoT terminal, a network device (or an IoT appserver) configured to connect the IoT terminal and the customer terminal(IoT app) through a wired/wireless network, and a gateway (for example,a Base Station (BS)) configured to transmit/receive packets between theIoT terminal and the network device.

In the IoT network, a method of supporting mobility of the IoT terminalhas not been presented since it is only considered that the number ofnetwork devices is one.

Further, since there is no server for managing subscription/opening ofthe IoT terminal in the current network, each network device locallymanages subscription-related information if two or more network devicesexist.

When the IoT terminal moves to a BS of another network device, which isnot the network device managing its own subscription-relatedinformation, a call processing process cannot be performed and thus thecall processing fails.

Further, when the IoT terminal moves to a boundary area between BSsconnected to different network devices, the different network devicesoverlappingly process the call of the IoT terminal, so that the resourceefficiency is inevitably reduced.

Meanwhile, the IoT network includes a plurality of IoT terminals. If theplurality of IoT terminals simultaneously moves to one network, the onenetwork is overloaded, so that trouble-free IoT services cannot beprovided

Accordingly, the present disclosure proposes a routing method betweennetworks for supporting mobility of the IoT terminal to implement a callprocessing method suitable for the IoT network.

SUMMARY

An aspect of the present disclosure is to support mobility of the IoTterminal to implement a call processing method suitable for the IoTnetwork.

In accordance with an aspect of the present disclosure, a network deviceis provided. The network device includes: an identification unit,implemented by a processor and including electrical circuits orintegrated circuits, configured to identify whether specific informationis included in an uplink message received from a specific terminaldevice, where the specific information includes subscription-relatedinformation indicating that (i) the specific terminal device has asubscription to a specific network device among the plurality of networkdevices and (ii) the specific terminal device is locally managed by thespecific network device; a determination unit, implemented by aprocessor and including electrical circuits or integrated circuits,configured to determine whether to route the uplink message on the basisof the identification of the specific information; and a decision unit,implemented by a processor including electrical circuits or integratedcircuits, configured to decide the specific network device to which theuplink message is routed on the basis of the specific information whenrouting the uplink message is determined. Herein, each network device ofthe network devices in the network system locally manages terminaldevices which subscribes to each network device.

In accordance with another aspect of the present disclosure, the methodoperating a network device in a network system including a plurality ofnetwork devices, comprises: identifying whether specific information isincluded in an uplink message received from a specific terminal device,wherein the specific information includes subscription-relatedinformation indicating that (i) the specific terminal device has asubscription to a specific network device among the plurality of networkdevices and (ii) the specific terminal device is locally managed by thespecific network device; determining whether to route the uplink messageon the basis of the identification of the specific information; anddeciding the specific network device to which the uplink message isrouted on the basis of the specific information when routing the uplinkmessage is determined. Herein each network device of the network devicesin the network system locally manages terminal devices which subscribesto each network device.

In accordance with another aspect of the present disclosure, a networkdevice is provided. The network device includes: a receiver, implementedby a processor and including electrical circuits or integrated circuits,configured to receive a response packet of a specific downlink packettransmitted to a terminal device; a decision unit, implemented by aprocessor and including electrical circuits or integrated circuits,configured to analyze whether the response packet indicates the specificdownlink packet is generated by a specific network device among theplurality of network devices in the network system; a routing unit,implemented by a processor and including electrical circuits orintegrated circuits, configured to route the response packet to thespecific network device when the specific network device is a networkdevice other than the network device receiving the response packet.

In accordance with another aspect of the present disclosure, a method ofoperating a network device in a network system including a plurality ofnetwork devices is provided. The method includes: receiving a responsepacket of a specific downlink packet transmitted to a terminal device;analyzing whether the response packet indicates the specific downlinkpacket is generated by a specific network device among the plurality ofnetwork devices in the network system; and routing the response packetto the specific network device when the specific network device is anetwork device other than the network device receiving the responsepacket.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of the presentdisclosure will be more apparent from the following detailed descriptiontaken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates an IoT network structure to which the presentdisclosure is applied;

FIG. 2 illustrates a situation in which mobility of the existing IoTterminal is not supported;

FIG. 3 is a block diagram illustrating the configuration of a networkdevice according to an embodiment of the present disclosure;

FIG. 4 is a block diagram illustrating the configuration of the networkdevice according to a detailed embodiment of the present disclosure;

FIG. 5 is a flowchart illustrating a routing operation method betweennetwork devices according to an embodiment of the present disclosure;

FIG. 6 is a flowchart illustrating a method of operating the networkdevice according to an embodiment of the present disclosure;

FIG. 7 is a block diagram illustrating the configuration of the networkdevice according to another embodiment of the present disclosure;

FIG. 8 illustrates a first method of allocating a token according toanother embodiment of the present disclosure;

FIG. 9 is a flowchart illustrating the operation in which the networkdevice routes a response packet (TxACK) according to another embodimentof the present disclosure;

FIG. 10 is a block diagram illustrating the configuration of the networkdevice according to another embodiment of the present disclosure;

FIG. 11 illustrates a second method of allocating a token according toanother embodiment of the present disclosure; and

FIG. 12 is a flowchart illustrating the operation in which the networkdevice routes a response packet (TxACK) according to another embodimentof the present disclosure.

DETAILED DESCRIPTION

It should be noted that the technical terms as used herein are merelyused for describing particular embodiments, and are not intended tolimit the scope of the present disclosure. Further, the technical termsin the specification should be construed as a meaning generallyunderstood by those skilled in the art unless the terms are defined asanother meaning and should not be construed as an excessively inclusivemeaning or an excessively exclusive meaning. When a technical term usedin the specification is an incorrect technical term which does notaccurately express the idea of the present disclosure, the technicalterm should be replaced with the correct technical term which can beunderstood by those skilled in the art. Further, the general terms usedin the present disclosure should be interpreted in the context accordingto the dictionary definition and should not be construed as possessingan excessively limited meaning.

In addition, a singular expression used in the specification includes aplural expression as long as they are clearly distinguished in thecontext. In the present disclosure, the term “comprise” or “include”should not be construed as necessarily including all of various elementsor various steps disclosed herein, and it should be understood that someof the elements or steps may not be included, or additional elements orsteps may be further included.

In addition, although terms including ordinal numbers such as first,second, and the like may be used to describe various elements, theelements should not be restricted by the terms. The terms are usedmerely for the purpose to distinguish an element from the otherelements. For example, a first element may be termed a second element,and similarly, a second element may be termed a first element withoutdeparting from the scope of the present disclosure.

Hereinafter, embodiments of the present disclosure will be described indetail with reference to the accompanying drawings, equal or similarelements are assigned an equal reference numeral, and an overlappingdescription thereof will be omitted.

Further, in the following description of the technology of the presentdisclosure, a detailed description of known technologies incorporatedherein will be omitted when it may make the subject matter of thepresent disclosure rather unclear. Further, it should be noted that theaccompanying drawings are intended only for the easy understanding ofthe technical idea of the present disclosure, and the technical ideashould not be construed as being limited by the accompanying drawings.

Hereinafter, embodiments of the present disclosure will be described indetail with reference to the accompanying drawings. In adding referencenumerals to elements in each drawing, the same elements will bedesignated by the same reference numerals, if possible, although theyare shown in different drawings. Further, in the following descriptionof the present disclosure, a detailed description of known functions andconfigurations incorporated herein will be omitted when it is determinedthat the description may make the subject matter of the presentdisclosure rather unclear.

Hereinafter, embodiments of the present disclosure will be describedwith reference to the accompanying drawings.

FIG. 1 illustrates a structure of an Internet of Things (IoT) network towhich the present disclosure is applied.

The structure of the IoT network consists of remote IoT terminals 100(for example, terminals 1, 2, . . . N), a customer terminal (not shown)configured to have an IoT app installed therein to control the IoTterminals and remotely identify data of the IoT terminals, networkdevices 200 (IoT app servers) (for example, network devices 1, 2, 3, . .. M) configured to connect the IoT terminals and the customer terminal(IoT app) through a wired/wireless network, and gateways (for example,BSs 1, 2, . . . L) configured to transmit/receive messages between theIoT terminal 100 and the network device 200.

In the structure of the IoT network, since there is no server designatedfor managing subscription/opening of the IoT terminals, the networkdevice individually manages subscription-related information of the IoTterminals.

That is, although two or more network devices exist in the structure ofthe IoT network, there is a limitation on supporting mobility of the IoTterminals like in the case where the number of network devices is one,since the network devices locally manage subscription-relatedinformation of the IoT terminals.

Hereinafter, a situation in which mobility of the IoT terminal is notsupported in the structure of the IoT network in which there are two ormore network devices will be described with reference to FIG. 2.

It is assumed that network device 1 manages subscription-relatedinformation of terminal 1 and network device 2 managessubscription-related information of terminal 2 in FIG. 2.

In {circle around (1)} of FIG. 2, terminal 1 moves to BS 2 connected tonetwork device 2.

In this case, network device 2 receives a request for processing a callby receiving an uplink packet (an uplink message) from terminal 1.However, network device 2 fails to perform a call processing processsince network 1 cannot identify subscription-related information ofterminal 1.

That is, only network 1 manages the subscription-related information ofterminal 1. Accordingly, when terminal 1 moves to network device 2 andmakes a request for call processing, the call processing fails.

In {circle around (2)} of FIG. 2, when terminal 1 moves to BS 2connected to network device 2 and transmits an uplink packet (an uplinkmessage), network device 2 is overloaded due to simultaneous access of aplurality of terminals and thus network device 2 may not perform callprocessing nor other functions of the IoT service.

In {circle around (3)} of FIG. 2, terminal 1 moves to a boundary areabetween BS 1 connected to network device 1 and BS 2 connected to networkdevice 2.

In this case, all of network devices 1 and 2 receive a request for callprocessing by receiving an uplink message from terminal 1.

At this time, network device 1 performs the call processing for theuplink message on the basis of subscription-related information ofterminal 1. However, network device 2 cannot identify thesubscription-related information of terminal 1 and thus cannot succeedin call processing, but may perform a process of attempting thecorresponding procedure according to the request for call processing.

As a result, when terminal 1 moves to the boundary area between BSs 1and 2 connected to different network devices, all of network devices 1and 2 overlappingly perform the process related to the call processing.

Accordingly, the present disclosure proposes a call processing methodsuitable for the IoT network capable of supporting mobility of the IoTterminal.

The network device according to an embodiment of the present disclosurewill be described in detail with reference to FIG. 3.

A network device 200 according to the present disclosure includes areceiver 210 configured to receive an uplink packet related to aspecific terminal, which has moved from another network device, adetermination unit 220 configured to determine a specific network deviceto which the uplink packet is routed on the basis of the uplink packet,and a routing unit 230 configured to route the uplink packet to thespecific network device. The network device 200 is implemented by, orincludes, one or more processors, which including electrical circuits orintegrates circuits, and/or application-specific integrated circuits(ASICs). Other components of the network device 200, such as each of thereceiver 210, the determination unit 220 and the routing unit 230 areimplemented by, or includes, one or more processors, which includingelectrical circuits or integrates circuits, and/or application-specificintegrated circuits (ASICs). The receiver 210 includes one or morenetwork interfaces (e.g., communication modem chip(s) comprisingapplication-specific integrated circuits (ASICs)) including, but notlimited to, cellular, Wi-Fi, LAN, WAN, CDMA, WCDMA, GSM, LTE and EPCnetworks, and cloud computing networks. The network device 200 furthercomprises input units such as one or more buttons, a touch screen, a micand so on, and output units such as a display, an indicator and so on(not shown).

At this time, the uplink packet related to the specific terminal may bean uplink message such as a join message or a normal report messagetransmitted from the specific terminal.

Alternatively, when an IoT BS receives the downlink packet transmittedfrom the network device 200 to be transmitted to the specific terminaland transmits the downlink packet to the specific terminal, the uplinkpacket related to the specific terminal may be a response packet (TxACK)transmitted to the network device 200 for downlink packet processing byan IoT BS,

Hereinafter, the network device according to a detailed embodiment ofthe present disclosure will be described in detail with reference toFIG. 4.

A network device 200A according to the present disclosure includes anidentification unit 210A configured to identify specific information ofan uplink message received from a specific terminal, a determinationunit 220A configured to determine whether the uplink message is routedon the basis of the identification result of the specific information,and a decision unit 230A configured to, when it is determined to routethe uplink message, decide a specific network device to which the uplinkmessage is routed on the basis of the specific information. The networkdevice 200A is implemented by, or includes, one or more processors,which including electrical circuits or integrates circuits, and/orapplication-specific integrated circuits (ASICs). Other components ofthe network device 200, such as each of the identification unit 210A,the determination unit 220A and the decision unit 230A are implementedby, or includes, one or more processors, which including electricalcircuits or integrates circuits, and/or application-specific integratedcircuits (ASICs). The network device 200A further comprises input unitssuch as one or more buttons, a touch screen, a mic and so on, and outputunits such as a display, an indicator and so on (not shown).

Further, the network device 200A according to the present disclosure mayfurther include a transmitter 240A configured to transmit the uplinkmessage to the specific network device. The transmitter 240A includesone or more network interfaces (e.g., communication modem chip(s)comprising application-specific integrated circuits (ASICs)) including,but not limited to, cellular, Wi-Fi, LAN, WAN, CDMA, WCDMA, GSM, LTE andEPC networks, and cloud computing networks.

The identification unit 210A identifies specific information of theuplink message received from the specific terminal.

The specific terminal may be any one of the terminals 1, 2, 3 . . . Nillustrated in FIG. 1.

Specifically, the specific terminal is defined as a terminal that movesto another network device and transmits an uplink packet (an uplinkmessage), where the another network is not the network device managingsubscription-related information of the specific terminal amongterminals 1, 2, 3 . . . N.

For example, when terminal 1 experiences a subscription/opening processin order to use the IoT service, network device 1 initially involved inthe subscription/opening of terminal 1 manages subscription-relatedinformation of terminal 1.

At this time, a terminal identifier (hereinafter, referred to as aDevice Extend Unique Identifier (DevEUI)) of terminal 1 and a networkdevice identifier (hereinafter, referred to as a Network Server ID(NSID)) of network device 1 initially involved in subscription/openingof terminal 1 are mapped to each other. The terminal identifier (DevEUI)is determined in a format of 64 bits defined by IEEE.

That is, in order to support mobility of terminal 1, the terminalidentifier (DevEUI) of terminal 1 and the network device identifier(NSID) of network device 1 are mapped to each other and stored in amapping table when terminal 1 is subscribed to/open.

Further, in the present disclosure, mapping information stored in themapping table is shared by all network devices 1, 2, 3 . . . M.

In such a situation, when terminal 1 moves to another network device 2,which is not network device 1 managing subscription-related informationof terminal 1, and transmits the uplink message, terminal 1 is aspecific terminal.

Hereinafter, for convenience of description, a detailed configuration ofnetwork device 2 configured to perform routing in order to supportmobility of terminal 1 using network device 1 initially involved insubscription/opening of the specific terminal (terminal 1) will bedescribed in detail.

That is, the network device 200A described below is network device 2.

The identification unit 210A receives an uplink packet, that is, anuplink message from terminal 1 and identifies specific information fromthe received uplink message.

The uplink message may be one of a join message, which terminal 1transmits to make a request for joining in the network when power isfirst turned on, and a normal report message, which terminal 1 transmitsto report data after the join procedure is completed.

The join message is transmitted to the network device by terminal 1 tomake a request for joining when terminal 1 is first turned on, andincludes a terminal identifier (DevEUI), an application identifier(application extend unique identifier), and a random value generated byterminal 1.

When receiving the join message from terminal 1, network device 2performs the join procedure for terminal 1 and allocates a terminaladdress (hereinafter, referred to as a DevAddr) to terminal 1 so thatterminal 1 can be distinguished from other terminals.

The normal report message, which terminal 1 transmits after thecompletion of the join procedure, includes the terminal address(DevAddr), which network device 2 allocates to terminal 1, instead ofthe terminal identifier (DevEUI).

The terminal address (DevAddr) is expressed in 32 bits and defined in aformat shown in [Table 1] below.

TABLE 1 Device Address (32 bits) NwkID (7 bits) (F1) NwkAddr (25 bits)(F2) Division according to each NSID (5 bits) IDs per NS (20 bits)nation or business after allocated

That is, the terminal address (DevAddr) includes a field (F1) forindicating a network identifier (hereinafter, referred to as NwkID) fordivision according to each nation or business after allocated by networkdevice 2 and a field (F2) for indicating a network address (hereinafter,referred to as NwkAddr).

At this time, the network device identifier (NSID) of network device 1is allocated to upper 5 bits in the 25 bits of the network address(NwkAddr).

At this time, when network device 2 allocates the terminal address(DevAddr) to terminal 1, network device 2 may allocate the networkdevice identifier (NSID) of network device 1 to upper 5 bits of thefield (F2) within the network address (NwkAddr) since network device 2shares and knows mapping information (the terminal identifier (DevEUI)of terminal 1—the network device identifier (NSID) of network device 1)stored in the mapping table.

Referring back to the identification unit 210A, when the uplink messagereceived from terminal 1 is the join message, the identification unit210A identifies the terminal identifier (DevEUI) included in the joinmessage as specific information.

When the uplink message received from terminal 1 is the normal reportmessage, the identification unit 210A identifies the terminal address(DevAddr) included in the normal report message as specific information.

The determination unit 220A determines whether to route the uplinkmessage on the basis of the identification result of the specificinformation.

More specifically, when the uplink message is the join message, thedetermination unit 220A identifies the network device identifier (NSID)pre-allocated to the terminal identifier (DevEUI) on the basis ofmapping information stored in the mapping table.

Further, the determination unit 220A determines whether to route thejoin message on the basis of a result of comparison between the networkdevice identifier (NSID) pre-allocated to the terminal identifier(DevEUI) and its own network device identifier.

When the network device identifier (NSID) pre-allocated to the terminalidentifier (DevEUI) and its own network device identifier match eachother, the determination unit 220A processes the join message by itselfwithout routing the join message.

When the network device identifier (NSID) pre-allocated to the terminalidentifier (DevEUI) and its own network device identifier do not matcheach other, the determination unit 220A determines to route the joinmessage.

Meanwhile, when the uplink message is the normal report message, thedetermination unit 220A determines whether to route the normal reportmessage on the basis of a result of comparison between the networkdevice identifier (NSID) pre-allocated to the terminal address (DevAddr)and its own network device identifier.

That is, when the network device identifier (NSID) pre-allocated to theterminal address (DevAddr) and its own network device identifier matcheach other, the determination unit 220A processes the normal reportmessage by itself without routing the normal report message.

When the network device identifier (NSID) pre-allocated to the terminaladdress (DevAddr) and its own network device identifier do not matcheach other, the determination unit 220A determines to route the normalreport message.

When it is determined to route the uplink message (the join message orthe normal report message), the decision unit 230A determines a specificnetwork device to which the uplink message is routed on the basis ofspecific information.

More specifically, when the uplink message is the join message, thedecision unit 230A determines, as the specific network device, networkdevice 1 having the network device identifier (NSID) pre-allocated tospecific information, that is, the terminal identifier (DevEUI).

Meanwhile, when the uplink message is the normal report message, thedecision unit 230A determines, as the specific network device, networkdevice 1 having the network device identifier (NSID) pre-allocated tospecific information, that is, the terminal address (DevAddr) ofterminal 1.

In the above-described structure of the IoT network in FIG. 1, when thenetwork device initially involved in subscription/opening of terminal 1is network device 1, the specific network device determined on the basisof specific information of the uplink message (the join message or thenormal report message) is network device 1.

When the specific network device to which the message is routed isdetermined, the transmitter 240A routes the join message to the specificnetwork device if the uplink message is the join message and route thenormal report message to the specific network device if the uplinkmessage is the normal report message.

As a result, in the case in which terminal 1 moves to network device 2,which is not network device 1 initially involved in subscription/openingof terminal 1, and transmits the uplink message, if the uplink messageis the join message, network device 2 identifies the terminal identifier(DevEUI) included in the join message as specific information,identifies the network device identifier (NSID) pre-allocated to theterminal identifier (DevEUI) through the mapping table, determineswhether to route the join message and the specific network device, androutes the join message to the specific network device.

Meanwhile, in the case in which terminal 1 moves to network device 2,which is not network device 1 initially involved in subscription/openingof terminal 1, and transmits the uplink message, if the uplink messageis the normal report message, network device 2 identifies the terminaladdress (DevAddr) included in the normal report message as specificinformation, identifies the network device identifier (NSID)pre-allocated to the terminal address (DevAddr), determines whether toroute the normal report message and the specific network device, androutes the normal report message to the specific network device.

Meanwhile, it has been described that the routing function betweennetwork devices for supporting mobility of the IoT terminal is performedinside the network device 200A according to an embodiment of the presentdisclosure, but the present disclosure is not limited thereto.

That is, the routing function between network devices for supportingmobility of the IoT terminal according to the present disclosure may beimplemented by a Mobility Management (MM) module, which is a separateindependent entity located outside the network device 200A.

Hereinafter, a method of operating the network device according to anembodiment of the present disclosure will be described with reference toFIGS. 5 and 6.

FIG. 5 is a flowchart illustrating a routing operation method betweennetwork devices according to an embodiment of the present disclosure.

In FIG. 5, as described above, terminal 1 is the specific terminal,network device 1 is the network device initially involved insubscription/opening of terminal 1, and network device 2 is the networkdevice that performs the routing operation on the basis of the uplinkmessage received from terminal 1.

According to the present disclosure, terminal 1 transmits the uplinkmessage in a broadcast scheme in S1.

At this time, when terminal 1 moves to a BS (not shown) of networkdevice 2 and transmits the uplink message, network device 2 receives theuplink message from terminal 1.

According to the present disclosure, network device 2 identifiesspecific information from the uplink message received from terminal 1 inS2.

The uplink message may be one of a join message, which terminal 1transmits to make a request for joining when power is first turned on,and a normal report message, which terminal 1 transmits to periodicallyreport data after the join procedure is completed.

According to the present disclosure, when the uplink message receivedfrom terminal 1 is the join message, network device 2 identifies aterminal identifier (DevEUI) included in the join message as specificinformation.

Meanwhile, according to the present disclosure, when the uplink messagereceived from terminal 1 is the normal report message, network device 2identifies the terminal address (DevAddr) included in the normal reportmessage as specific information.

According to the present disclosure, network device 2 identifies whetherto route the uplink message on the basis of the identification result ofthe specific information in S3.

More specifically, network device 2 may identify a network deviceidentifier (NSID) of the network device initially involved insubscription/opening of terminal 1 on the basis of the specificinformation identified from the uplink message.

That is, network device 2 may identify the network device identifier(NSID) pre-allocated to specific information, that is, the terminalidentifier (DevEUI) in mapping information stored in the mapping tablewhen the uplink message is the join message, and may identify thenetwork device identifier (NSID) pre-allocated to the terminal address(DevAddr) when the uplink message is the normal report message.

Accordingly, network device 2 determines whether to perform routing bycomparing the network device identifier (NSID), which is identified onthe basis of the specific information identified from the uplinkmessage, and its own network device identifier.

When the pre-allocated network device identifier (NSID) and its ownnetwork device identifier match each other on the basis of thecomparison result in step S3, network device 2 processes the joinmessage/normal report message by itself without routing the same in S6.

When the pre-allocated network device identifier (NSID) and its ownnetwork device identifier do not match each other on the basis of thecomparison result in step S3, network device 2 determines to route thejoin message/normal report message.

Further, network device 2 determines a specific network device to whichthe uplink message is routed on the basis of the specific information ofthe uplink message in S4.

More specifically, when the uplink message is the join message, networkdevice 2 determines, as the specific network device, network device 1having the network device identifier (NSID) pre-allocated to thespecific information, that is, the terminal identifier (DevEUI).

Meanwhile, when the uplink message is the normal report message, networkdevice 2 determines, as the specific network device, network device 1having the network device identifier (NSID) pre-allocated to thespecific information, that is, the terminal address (DevAddr) ofterminal 1.

In the above-described structure of the IoT network in FIG. 1, when thenetwork device initially involved in subscription/opening of terminal 1is network device 1, the specific network device determined on the basisof specific information of the uplink message (the join message or thenormal report message) is network device 1.

When the specific network to which the message is routed is determined,network device 2 may route the uplink message (the join message or thenormal report message) to network device 1, which has been determined asthe specific network device, in S5.

At this time, after the specific network device to which the uplinkmessage is routed is determined, network device 2 may additionallyperform a process of identifying whether the determined specific networkdevice, that is, network device 1, cannot accept a call.

That is, network device 2 may inquire the specific network device aboutwhether to accept a call, and when the specific network device canaccept the call, route the uplink message to the specific networkdevice, that is, network device 1 in S5. Network device 1 may receiveand process the uplink message of terminal 1 in S7.

However, network device 2 may inquire the specific network device aboutwhether to accept a call, and when the specific network device cannotaccept the call, drop the uplink message without routing the uplinkmessage to the specific network device, that is, network device 1.

FIG. 6 is a flowchart illustrating a method of operating the networkdevice according to an embodiment of the present disclosure.

In FIG. 6 also, terminal 1 is the specific terminal, network device 1 isthe network device initially involved in subscription/opening ofterminal 1, and network device 2 is the network device that performs therouting operation on the basis of the uplink message received fromterminal 1.

The identification unit 210A of network device 2 according to thepresent disclosure receives the uplink message from terminal 1 andidentifies specific information from the received uplink message in S10and S20.

The uplink message may be one of a join message, which terminal 1transmits to make a request for joining when power is first turned on,and a normal report message, which terminal 1 transmits to periodicallyreport data after the join procedure is completed.

That is, when the uplink message received from terminal 1 is the joinmessage, the identification unit 210A identifies the terminal identifier(DevEUI) included in the join message as specific information.

Meanwhile, when the uplink message received from terminal 1 is thenormal report message, the identification unit 210A identifies theterminal address (DevAddr) included in the normal report message asspecific information.

When the specific information is identified from the uplink message, thedetermination unit 220A of network device 2 according to the presentdisclosure determines whether to route the uplink message on the basisof the identification result of the specific information.

More specifically, the determination unit 220A determines whether theuplink message is the join message in S30.

At this time, the determination of whether the uplink message is thejoin message is used as a reference for determining a transmissioncommand to transmit the join message according to the communicationstandard in order to provide the IoT service and field value informationdefining a message type within the transmission command, or when anidentifier for being distinguished from the normal report message isseparately allocated, may be performed using the allocated identifier.

When the uplink message is the join message based on the determinationresult of step S30, the determination unit 220A detects the networkdevice identifier (NSID) pre-allocated to the terminal identifier(DevEUI) within the join message on the basis of mapping stored in themapping table in S40.

Thereafter, the determination unit 220A determines whether to route thejoin message on the basis of a result of comparison between the networkdevice identifier (NSID) pre-allocated to the terminal identifier(DevEUI) and its own network device identifier.

That is, when the network device identifier (NSID) pre-allocated to theterminal identifier (DevEUI) and its own network device identifier matcheach other, the determination unit 220A determines to process the joinmessage by itself without routing the join message.

On the other hand, when the network device identifier (NSID)pre-allocated to the terminal identifier (DevEUI) and its own networkdevice identifier do not match each other, the determination unit 220Adetermines to route the join message.

When it is determined to route the join message, the decision unit 230Aof network device 2 according to the present disclosure decides networkdevice 1 having the network device identifier (NSID) pre-allocated tothe terminal identifier (DevEUI) as a specific network device among theplurality of network devices 1, 2, 3, . . . M in S50.

The transmitter 240A of network device 2 according to the presentdisclosure routes the join message to network device 1, which is thespecific network device, in S60.

Meanwhile, when the uplink message is not the join message based on thedetermination result of step S30, the determination unit 220A of networkdevice 2 according to the present disclosure determines that the uplinkmessage is the normal report message and detects the network deviceidentifier (NSID) pre-allocated to the terminal address (DevAddr) withinthe normal report message in S70.

Thereafter, the determination unit 220A of network device 2 according tothe present disclosure determines whether to route the normal reportmessage on the basis of a result of comparison between the networkdevice identifier (NSID) pre-allocated to the terminal address (DevAddr)and its own network device identifier.

That is, when the network device identifier (NSID) pre-allocated to theterminal address (DevAddr) and its own network device identifier matcheach other, the determination unit 220A determines to process the normalreport message by itself without routing the normal report message.

On the other hand, when the network device identifier (NSID)pre-allocated to the terminal address (DevAddr) and its own networkdevice identifier do not match each other, the determination unit 220Adetermines to route the normal report message.

When it is determined to route the normal report message, the decisionunit 230A of network device 2 according to the present disclosuredecides network device 1 having the network device identifier (NSID)pre-allocated to the terminal address (DevAddr) as a specific networkdevice among the plurality of network devices 1, 2, 3, . . . M in S80.

The transmitter 240A of network device 2 according to the presentdisclosure routes the normal report message to network device 1, whichis the specific network device, in S90.

As described above, according to the present disclosure, mobility of theterminal can be supported even in the structure of the current IoTnetwork in which there is no server designated for managingsubscription-related information of the terminal, and thus it ispossible to be free from problems ({circle around (1)}, {circle around(2)}, and {circle around (3)} of FIG. 2) about failure in callprocessing, duplication of call processing, and overload due tosimultaneous call access.

According to the present disclosure, an effect of improving theperformance of the IoT service can be derived by proposing a routingmethod between network devices capable of making call processingsuitable for the IoT network, which can support mobility of theterminal, possible.

According to another aspect of the structure of the IoT network, whenthe network device is to transmit the downlink packet to the IoTterminal, the network device transmits the downlink packet to one IoTgateway device (BS) pre-selected for the IoT terminal and the one BSreceiving the downlink packet transmits the downlink packet to the IoTterminal.

In order to transmit the downlink packet by the IoT network devicethrough such a method, call processing between the network device andthe BS should be performed. For this, a Gateway Message Protocol (GWMP)is used as a call processing protocol in the structure of the IoTnetwork.

Particularly, in the case of GWMP v2, when the downlink packet isreceived from the network device, the BS generates a response packet(TxACK) including error state information on processing of the downlinkpacket of the BS and transmits the response packet to the networkdevice, which improves completeness of transmission of the downlinkpacket.

The error state information includes codes for indicating normalprocessing, downlink packet collision, too late, and too early as shownin [Table 2] below.

TABLE 2 Text Description TOO_LATE Rejected because it was already toolate to program this packet for downlink TOO_EARLY Rejected becausedownlink packet timestemp was received by the gateway too long beforethe scheduled transmission time COLLISION_PACKET Rejected because therewas already a packet programmed in requested timeframe COLLISION_BEACONRejected because there was already a beacon planned in requestedtimeframe TX_FREQ Rejected because requested frequency is not supportedby TX RF chain TX_POWER Rejected because requested power is notsupported by gateway GPS_UNLOCKED Rejected because GPS is unlocked, soGPS timestamp cannot be used

The response packet (TxACK) includes a token as an identifier foridentifying the response packet (TxACK), where the token is informationmapped between the network device and the BS in one-to-onecorrespondence.

That is, the network device transmitting the downlink packet allocatesthe token to identify the response packet (TxACK) but, at this time,another network device within the IoT network may allocate the sametoken to identify the response packet (TxACK).

As described above, even though different network devices allocate thesame (duplicated) token, it is not a major problem in the IoT networkenvironment in which mobility of the IoT terminal is not supported sincecall processing inevitably fails anyway.

However, in the IoT network environment in which mobility of the IoTterminal is supported according to the present disclosure, a problem mayoccur in that a network device, to which the response packet (TxACK) isrouted, cannot be recognized due to the duplicated token allocated bydifferent network devices.

Accordingly, the present disclosure proposes a method of routing theresponse packet (TACK) between network devices suitable for the IoTnetwork environment in which mobility of the IoT terminal is supported.

Hereinafter, the network device according to an embodiment of thepresent disclosure will be described in detail with reference to FIG. 7.

A network device 200B according to the present disclosure includes areceiver 210B configured to receive a response packet of a specificdownlink packet transmitted to the terminal, a decision unit 220Bconfigured to decide a specific network device allocated to the terminalon the basis of on an analysis result of the response packet, and arouting unit 230B configured to route the response packet to thespecific network device. The network device 200B is implemented by, orincludes, one or more processors, which including electrical circuits orintegrates circuits, and/or application-specific integrated circuits(ASICs). Other components of the network device 200B, such as each ofthe receiver 210B, the decision unit 220B, the routing unit 230B areimplemented by, or includes, one or more processors, which includingelectrical circuits or integrates circuits, and/or application-specificintegrated circuits (ASICs). The receiver 210B includes one or morenetwork interfaces (e.g., communication modem chip(s) comprisingapplication-specific integrated circuits (ASICs)) including, but notlimited to, cellular, Wi-Fi, LAN, WAN, CDMA, WCDMA, GSM, LTE and EPCnetworks, and cloud computing networks. The network device 200B furthercomprises input units such as one or more buttons, a touch screen, a micand so on, and output units such as a display, an indicator and so on(not shown).

Further, the network device 200B according to the present disclosure mayfurther include a transmitter 240B configured to transmit the specificdownlink packet and the response packet.

The specific downlink packet is a downlink packet which another networkdevice transmits to a terminal (hereinafter, a specific terminal) movingto the another network device, where the another network is not thenetwork device managing subscription-related information of the terminalamong the terminals 1, 2, 3 . . . N illustrated in FIG. 1.

Hereinafter, for convenience of description, it is assumed that terminal2 among terminals 1, 2, 3 . . . N illustrated in FIG. 1 is described asthe specific terminal and terminal 2 moves from network device 2(network device 2 to which terminal 2 is allocated (which accommodatesterminal 2)) managing subscription-related information of terminal 2 toanother network device, that is, network device 1.

The specific downlink packet which network device 2 is to transmit toterminal 2 includes a token allocated by network device 2 to identifythe response packet (TxACK) of the specific downlink packet.

The token is mapped between network device 2 and BS 2 connected theretoin one-to-one correspondence. Accordingly, when BS 2 receives thespecific downlink packet including the token, BS 2 generates a responsepacket (TxACK) including a token, which is the same as the tokenincluded in the specific downlink packet, and transfers the responsepacket (TxACK) to the network device 200B.

For example, when a specific downlink packet including a token (forexample, AAAAA1) is received from network device 2, BS 2 generates aresponse packet (TxACK) including a token, which is the same as thetoken (for example, AAAAA1) included in the specific downlink packet,and transfers the response packet (TxACK) to network device 2.

The response packet (TxACK) includes a version-related field 300 forstoring a protocol version, a token-related field 310 for storing atoken, an identifier-related field 320 for storing a response packetidentifier (TxACK ID), and an information indicating field 330 forstoring payload as shown in [Table 3] below.

TABLE 3 Protocol Token TxACK ID Payload (indicating Error Version (4bytes) information)

Meanwhile, the network device 200B according to an embodiment of thepresent disclosure is network device 1 to which terminal 2 moves in theassumed situation (in which terminal 2 moves from network device 2 tonetwork device 1).

Accordingly, hereinafter, it is understood that the network device 200Baccording to the present disclosure is network device 1.

The receiver 210B receives the response packet of the specific downlinkpacket.

Specifically, when the transmitter 240B transmits the specific downlinkpacket to BS 1, the receiver 210B receives the response packet (TxACK)of the specific downlink packet from BS 1.

In connection with this, FIG. 8 illustrates a first method of allocatinga token in order to implement routing of the response packet (TxACK)according to the present disclosure.

As illustrated in FIG. 8, network device 2 to which terminal 2 isallocated (which accommodates terminal 2) allocates a token to identifythe response packet (TxACK) of the specific downlink packet.

Hereinafter, the first method will be described of allocating the tokenthrough the response packet (TxACK) based on the fact that the token isallocated by network device 2 and then transmitted to network device 1with being inserted into the specific downlink packet, and the responsepacket (TxACK) therefore includes the same token as that of the specificdownlink packet.

Network device 2 newly defines the size of the token-related field 310within the response packet (TxACK) from 2 bytes to 4 bytes.

The newly defined token-related field 310 includes a first area 311having the size of 2 bytes for storing a network device identifier towhich the response packet (TxACK) is routed and a second area 312 havingthe size of 2 bytes for storing the existing token.

That is, network device 2 generates the specific downlink packetincluding its own network device identifier in the first area 311 andtransmits the specific downlink packet to network device 1.

Then, network device 1 transmits, through the transmitter 240B, thespecific downlink packet including the network device identifier ofnetwork device 2 to BS 1 connected to network device 1.

The receiver 210B receives the response packet (TxACK) of the specificdownlink packet from BS 1.

The decision unit 220B decides the specific network device on the basisof an analysis result of the response packet (TxACK).

More specifically, when the response packet (TxACK) is received, thedecision unit 220B detects the network device identifier included in thetoken-related field 310 within the response packet (TxACK).

That is, since the network device identifier to which the responsepacket (TxACK) is routed is stored in the first area 311 of thetoken-related field 310, the decision unit 220B detects the networkdevice identifier from the first area 311.

Thereafter, the decision unit 220B decides a network device having thedetected network device identifier as the specific network device towhich the response packet (TxACK) is routed.

That is, the decision unit 220B decides, as the specific network device,network device 2, which is a network device that matches the detectednetwork device identifier among the plurality of network devices 1, 2, 3. . . M illustrated in FIG. 1.

The routing unit 230B routes the response packet (TxACK) to the specificnetwork device.

That is, when network device 2 is determined as the specific networkdevice, the routing unit 230B routes the response packet (TxACK) tonetwork device 2 for call processing of the response packet (TxACK).

Hereinafter, a flow of the operation in which the network device routesthe response packet (TxACK) according to an embodiment of the presentdisclosure will be described in more detail with reference to FIG. 9.

Hereinafter, it is assumed that terminal 2 moves from network device 2(network device 2 to which terminal 2 is allocated (which accommodatesterminal 2)) managing subscription-related information of terminal 2 toanother network device, that is, network device 1.

As illustrated in FIG. 9, when terminal 2 allocated to (accommodated by)network device 2 moves to coverage of BS 1 connected to network device1, network device 2 allocates a token for identifying a response packet(TxACK) in order to transmit a specific downlink packet to terminal 2 inS100.

Specifically, network device 2 newly defines the size of thetoken-related field 310 within the response packet (TxACK) from 2 bytesto 4 bytes.

The newly defined token-related field 310 includes a first area 311having the size of 2 bytes for storing a network device identifier towhich the response packet (TxACK) is routed and a second area 312 havingthe size of 2 bytes for storing the existing token.

Network device 2 may generate the specific downlink packet including itsown network device identifier in the first area 311 and transmit thespecific downlink packet to network device 1 in S101. The specificdownlink packet is transmitted in the form of a message such as “PullResponse (token, Data)”.

When the specific downlink packet is received from network device 2,network device 1 transmits the specific downlink packet to BS 1connected to network device 1 to transmit the specific downlink packetto terminal 2 in S102.

Then, BS 1 identifies error state information detected during aprocessing process in which BS 1 receives the specific downlink packetfrom network device 1 and transmits the same to terminal 2.

Thereafter, BS 1 detects the token from the specific downlink packet,generates the response packet (TxACK) including the detected token andthe error state information, and transmits the response packet (TxACK)to network device 1 in S103.

For example, when an error is generated during the processing process inwhich BS 1 receives the specific downlink packet and transmits the sameto terminal 2, BS 1 detects the token from the specific downlink packet,identifies a code corresponding to the error in [Table 3], that is,error state information, generates the response packet (TxACK), andtransmits the response packet (TxACK) to network device 1.

Then, network device 1 detects the network device identifier included inthe token-related field 310 within the response packet (TxACK) in S104.

That is, since the network device identifier to which the responsepacket (TxACK) is routed is stored in the first area 311 of thetoken-related field 310, network device 1 may detect the network deviceidentifier from the first area 311.

Thereafter, network device 1 determines a network device having thedetected network device identifier as the specific network device inS105.

That is, network device 1 determines, as the specific network device towhich the response packet (TxACK) is routed, network device 2, which isa network device that matches the detected network device identifieramong the plurality of network devices 1, 2, 3 . . . M illustrated inFIG. 1.

Network device 1 routes the response packet (TxACK) to the specificnetwork device, that is, network device 2 in S106.

According to the first method, the existing problem of routing of theresponse packet (TxACK) that cannot be performed as allocation of theduplicated tokens by all network devices can be resolved. But there isstill a limitation in that a Message Protocol (GWMP), which is thestandard protocol Gateway, used for call processing between the networkdevice and the BS should be changed.

Accordingly, hereinafter, it will be described that a network device anda method by which the network device implements routing of the responsepacket (TACK) according to another embodiment of the present disclosurecan implement routing of the response packet (TACK) without changing thestandard protocol.

FIG. 10 is a block diagram illustrating the configuration of the networkdevice according to another embodiment of the present disclosure.

A network device 200C according to the present disclosure includes areceiver 210C configured to receive a response packet of a specificdownlink packet transmitted to the terminal, a decision unit 220Cconfigured to decide a specific network device allocated to the terminalon the basis of an analysis result of the response packet, and a routingunit 230C configured to route the response packet to the specificnetwork device.

Further, the network device 200C according to the present disclosure mayfurther include a transmitter 240C configured to transmit a specificdownlink packet and the response packet and a table generator 250Cconfigured to, when the downlink packet including a second token valueis received from the specific network device, generate a token table byallocating a first token value different from the second token value.

Hereinafter, it is assumed that terminal 2 moves from network device 2(network device 2 to which terminal 2 is allocated (which accommodatesterminal 2)) managing subscription-related information of terminal 2 toanother network device, that is, network device 1.

The receiver 210C receives the response packet of the specific downlinkpacket.

More specifically, when the transmitter 240C transmits the specificdownlink packet to BS 1, the receiver 210C receives the response packet(TxACK) of the specific downlink packet from BS 1.

In connection with this, FIG. 11 illustrates a second method ofallocating a token in order to implement routing of the response packet(TxACK) according to the present disclosure.

As illustrated in FIG. 11, network device 2 to which terminal 2 isallocated (which accommodates terminal 2) primarily allocates a token toidentify the response packet (TxACK) of the specific downlink packet.

At this time, the token value (second token value) primarily allocatedby network device 2 is allocated with the size of 2 bytes defined by theGateway Message Protocol (GWMP), which is the standard protocol used forcall processing between the network device and the BS.

That is, network device 2 allocates the second token value (for example,AAAAA1) in order to identify the response packet (TxACK), generatesspecific downlink packet 1 including the allocated second token value(for example, AAAAA1), and transfers specific downlink packet 1 tonetwork device 1.

Specific downlink packet 1 is transmitted in the form of a message suchas “Pull Response (primarily allocated token=second token value, Data)”.

When specific downlink packet 1 is received from network device 2,network device 1 detects the second token value (for example, AAAAA1)from the specific downlink packet and secondarily allocates anon-duplicated token, which is different from the second token value(for example, AAAAA1).

That is, network device 1 secondarily allocates a non-duplicated tokenvalue (first token value) (for example, BBBBB2) which is different fromthe second token value (for example, AAAAA1) detected from the specificdownlink packet.

Thereafter, network device 1 maps the primarily allocated token value(second token value) (for example, AAAAA1) and the secondarily allocatedtoken value (first token value) (for example, BBBBB2) and generates atoken table for routing the response packet (TxACK).

When the token table is completely generated, network device 1 generatesspecific downlink packet 2 by performing a replacement process such thatthe first token value (for example, BBBBB2) which network device 1secondarily allocates is included in specific downlink packet 1 insteadof the second token value (for example, AAAAA1) which network device 2primarily allocates.

Specific downlink packet 2 is transmitted in the form of a message suchas “Pull Response (secondarily allocated token=first token value,Data)”.

That is, network device 1 generates specific downlink packet 2 includingthe first token value (for example, BBBBB2) which network device 1secondarily allocates to identify the response packet (TxACK) andtransmits specific downlink packet 2 to BS 1.

The receiver 210C receives response packet 1 (TxACK) of specificdownlink packet 2 from BS 1. Response packet 1 (TxACK) is transmitted inthe form of a message such as “TxACK (secondarily allocated token=firsttoken value, error)”.

The decision unit 220C decides the specific network device on the basisof an analysis result of response packet 1 (TxACK).

More specifically, when response packet 1 (TxACK) is received, thedecision unit 220C detects the first token value (for example, BBBBB2)included in the token-related field 310 within response packet 1(TxACK).

That is, the decision unit 220C detects the second token value (forexample, AAAA1) mapped to the first token value (for example, BBBBB2)through a pre-stored token table and identifies that the detected secondtoken value (for example, AAAAA1) is allocated by network device 2.

Thereafter, the decision unit 220C decides network device 2 allocatingthe second token value (for example, AAAAA1) as a specific networkdevice to which response packet 1 (TxACK) is routed.

In this case, the decision unit 220C generates response packet 2 (TxACK)by performing a replacement process such that the second token value(for example, AAAAA1), which network device 2 primarily allocates, isincluded in response packet 1 (TxACK) instead of the first token value(for example, BBBBB2), which network device 1 secondarily allocates,included in the token-related field 310 within response packet 1(TxACK). Response packet 2 (TxACK) is transmitted in the form of amessage such as “TxACK (primarily allocated token=second token value,error)”.

The routing unit 230C routes response packet 2 (TxACK) to the specificnetwork device, that is, network device 2.

Hereinafter, a flow of the operation in which the network device routesthe response packet (TxACK) according to an embodiment of the presentdisclosure will be described in more detail with reference to FIG. 12.

Hereinafter, it is assumed that terminal 2 moves from network device 2(network device 2 to which terminal 2 is allocated (which accommodatesterminal 2)) managing subscription-related information of terminal 2 toanother network device, that is, network device 1.

As illustrated in FIG. 12, when terminal 2 allocated to (accommodatedby) network device 2 moves to coverage of BS 1 connected to networkdevice 1, network device 2 primarily allocates a token for identifying aresponse packet (TxACK) in order to transmit specific downlink packet 1to terminal 2 in S200.

That is, network device 2 allocates the second token value (for example,AAAAA1) in order to identify the response packet (TxACK), generatesspecific downlink packet 1 including the allocated second token value(for example, AAAAA1), and transfers specific downlink packet 1 tonetwork device 1 in S201.

Specific downlink packet 1 is transmitted in the form of a message suchas “Pull Response (primarily allocated token=second token value, Data)”.

When specific downlink packet 1 is received from network device 2,network device 1 detects the second token value (for example, AAAAA1)from specific downlink packet 1 and secondarily allocates anon-duplicated token, which is different from the second token value(for example, AAAAA1) in S202.

That is, network device 1 secondarily allocates a non-duplicated tokenvalue (first token value) (for example, BBBBB2) which is different fromthe second token value (for example, AAAAA1) detected from specificdownlink packet 1.

Thereafter, network device 1 maps the primarily allocated token value(second token value) (for example, AAAAA1) and the secondarily allocatedtoken value (first token value) (for example, BBBBB2) and generates atoken table for routing the response packet (TxAKC) in S203.

When the token table is completely generated, network device 1 generatesspecific downlink packet 2 by performing a replacement process such thatthe first token value (for example, BBBBB2) which network device 1secondarily allocates is included in specific downlink packet 1 insteadof the second token value (for example, AAAAA1) which network device 2primarily allocates in S204.

That is, network device 1 generates specific downlink packet 2 includingthe first token value (for example, BBBBB2) which network device 1secondarily allocates to identify the response packet (TxACK) andtransmits specific downlink packet 2 to BS 1 in S205.

Then, BS 1 identifies error state information detected during aprocessing process in which BS 1 receives specific downlink packet 2from network device 1 and transmits the same to terminal 2.

Thereafter, BS 1 detects the secondarily allocated first token value(for example, BBBBB2) from specific downlink packet 2, generatesresponse packet 1 (TxACK) including the detected first token value (forexample, BBBBB2) and the error state information, and transmits responsepacket 1 (TxACK) to network device 1 in S206.

Response packet 1 (TxACK) is transmitted in the form of a message suchas “TxACK (secondarily allocated token=first token value, error)”.

Then, network device 1 detects the first token value (for example,BBBBB2) included in the token-related field 310 within response packet 1(TxACK) in S207.

Thereafter, network device 1 may detect the second token value (forexample, AAAA1) mapped to the first token value (for example, BBBBB2)through the pre-stored token table and identify that the detected secondtoken value (for example, AAAAA1) is allocated by network device 2.

That is, network device 1 determines network device 2 allocating thesecond token value (for example, AAAAA1) as a specific network device towhich response packet 1 (TxACK) is routed in S208.

Network device 1 generates response packet 2 (TxACK) by performing areplacement process such that the second token value (for example,AAAAA1), which network device 2 primarily allocates, is included inresponse packet 1 (TxACK) instead of the first token value (for example,BBBBB2), which network device 1 secondarily allocates, included in thetoken-related field 310 within response packet 1 (TxACK). Responsepacket 2 (TxACK) is transmitted in the form of a message such as “TxACK(primarily allocated token=second token value, error)”.

Thereafter, network device 1 routes response packet 2 (TxACK) to thespecific network device, that is, network device 2 in S209.

As a result, according to exemplary various embodiments of the presentdisclosure, even when the IoT terminal moves to coverage of anothernetwork in the IoT network environment, the network device to which theIoT terminal is allocated (which accommodates the IoT terminal) can bedetermined as the network device to which the response packet (TxACK) ofthe downlink packet is routed on the basis of the analysis result of theresponse packet (TxACK) and thus the response packet (TxACK) can berouted to the determined network device.

Accordingly, the present disclosure can provide a differentiated servicequality by improving completeness of transmission of a message throughthe response packet (TxACK) in the IoT network environment in whichmobility of the IoT terminal is supported.

As described above, according to exemplary various embodiments of thepresent disclosure, the present application obtains advantageous effectsto derive an effect of improving performance of the IoT service byproposing a method of routing the response packet (TxACK) betweennetwork devices suitable for the IoT network environment in whichmobility of the IoT terminal is supported.

As described above, according to exemplary various embodiments of thepresent disclosure, the present application obtains advantageous effectsto derive an effect of improving performance of the IoT service byimplementing a method of processing a call (an uplink message or aresponse packet) suitable for the IoT network in which mobility of theIoT terminal is supported.

The implementations of the functional operations and subject matterdescribed in the present disclosure may be realized by a digitalelectronic circuit, by the structure described in the presentdisclosure, and the equivalent including computer software, firmware, orhardware including, or by a combination of one or more thereof.Implementations of the subject matter described in the specification maybe implemented in one or more computer program products, that is, one ormore modules related to a computer program command encoded on a tangibleprogram storage medium to control an operation of a processing system orthe execution by the operation.

A non-transitory computer-readable medium may be a machine-readablestorage device, a machine-readable storage substrate, a memory device, acomposition of materials influencing a machine-readable radio wavesignal, or a combination of one or more thereof.

In the specification, the term “system” or “device”, for example, coversa programmable processor, a computer, or all kinds of mechanisms,devices, and machines for data processing, including a multiprocessorand a computer. The processing system may include, in addition tohardware, a code that creates an execution environment for a computerprogram when requested, such as a code that constitutes processorfirmware, a protocol stack, a database management system, an operatingsystem, or a combination of one or more thereof.

A computer program (also known as a program, software, softwareapplication, script, or code) can be written in any form of programminglanguage, including compiled or interpreted languages, declarative orprocedural languages, and it can be deployed in any form, including as astand-alone program or module, a component, subroutine, or another unitsuitable for use in a computer environment. A computer program may, butneed not, correspond to a file in a file system. A program can be storedin a single file provided to the requested program, in multiplecoordinated files (for example, files that store one or more modules,sub-programs, or portions of code), or in a portion of a file that holdsother programs or data (for example, one or more scripts stored in amarkup language document). A computer program can be deployed to beexecuted on one computer or on multiple computers, including electricalcircuits or integrated circuits, that are located at one site ordistributed across a plurality of sites and interconnected by acommunication network.

A non-transitory computer-readable medium suitable for storing acomputer program command and data includes all types of non-volatilememories, media, and memory devices, for example, a semiconductor memorydevice such as an EPROM, an EEPROM, and a flash memory device, and amagnetic disk such as an external hard disk or an external disk, amagneto-optical disk, a CD-ROM, and a DVD-ROM disk. A processor and amemory may be added by a special purpose logic circuit or integratedinto the logic circuit.

The implementations of the subject matter described in the specificationmay be implemented in a calculation system including a back-endcomponent such as a data server, a middleware component such as anapplication server, a front-end component such as a client computerhaving a web browser or a graphic user interface which can interact withthe implementations of the subject matter described in the specificationby the user, or all combinations of one or more of the back-end,middleware, and front-end components. The components of the system canbe mutually connected by any type of digital data communication such asa communication network or a medium.

While the specification contains many specific implementation details,these should not be construed as limitations to the scope of the claimedinvention or of what may be claimed, but rather as descriptions offeatures that may be specific to particular embodiments of particulardisclosures. Certain features that are described in the specification inthe context of separate embodiments can also be implemented incombination in a single embodiment. Conversely, various features thatare described in the context of a single embodiment can also beimplemented in multiple embodiments separately or in any suitablesubcombination. Moreover, although features may be described above asacting in certain combinations and even initially claimed as such, oneor more features from a claimed combination can in some cases be excisedfrom the combination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

In addition, in the specification, the operations are illustrated in aspecific sequence in the drawings, but it should be understood that theoperations are not necessarily performed in the shown specific sequenceor that all shown operations are necessarily performed in order toobtain a preferable result. In a specific case, multitasking andparallel processing may be preferable. Furthermore, it should not beunderstood that a separation of the various system components of theabove-mentioned implementation is required in all implementations. Inaddition, it should be understood that the described program componentsand systems usually may be integrated in a single software package ormay be packaged in a multi-software product.

As described above, specific terms disclosed in the specification do notintend to limit the present disclosure. Therefore, while the presentdisclosure was described in detail with reference to the above-mentionedexamples, a person skilled in the art may modify, change, and transformsome parts without departing a scope of the present disclosure. Thescope of the present disclosure is defined by the appended claims to bedescribed later, rather than the detailed description. Accordingly, itwill be appreciated that all modifications or variations derived fromthe meaning and scope of the appended claims and their equivalents areincluded in the range of the present disclosure.

What is claimed is:
 1. A network device in a network system including aplurality of network devices, the network device comprising: anidentification unit, implemented by a processor and including electricalcircuits or integrated circuits, configured to identify whether specificinformation is included in an uplink message received from a specificterminal device, wherein the specific information includessubscription-related information indicating that (i) the specificterminal device has a subscription to a specific network device amongthe plurality of network devices and (ii) the specific terminal deviceis locally managed by the specific network device; a determination unit,implemented by a processor and including electrical circuits orintegrated circuits, configured to determine whether to route the uplinkmessage on the basis of the identification of the specific information;and a decision unit, implemented by a processor including electricalcircuits or integrated circuits, configured to decide the specificnetwork device to which the uplink message is routed on the basis of thespecific information when routing the uplink message is determined,wherein each network device of the network devices in the network systemlocally manages terminal devices which subscribes to each networkdevice.
 2. The network device of claim 1, wherein, when the uplinkmessage is a join message for joining of the specific terminal device innetwork, the specific information is a terminal identifier included inthe join message.
 3. The network device of claim 1, wherein, when theuplink message is a normal report message for report of the specificterminal device to network, the specific information is a terminaladdress included in the normal report message.
 4. The network device ofclaim 1, wherein, when it is identified that the specific network devicecannot accept a call, the network device drops the uplink message.
 5. Amethod of operating a network device in a network system including aplurality of network devices, the method comprising: identifying whetherspecific information is included in an uplink message received from aspecific terminal device, wherein the specific information includessubscription-related information indicating that (i) the specificterminal device has a subscription to a specific network device amongthe plurality of network devices and (ii) the specific terminal deviceis locally managed by the specific network device; determining whetherto route the uplink message on the basis of the identification of thespecific information; and deciding the specific network device to whichthe uplink message is routed on the basis of the specific informationwhen routing the uplink message is determined, wherein each networkdevice of the network devices in the network system locally managesterminal devices which subscribes to each network device.
 6. The methodof claim 5, wherein, when the uplink message is a join message forjoining of the specific terminal device in network, the specificinformation is a terminal identifier included in the join message. 7.The method of claim 5, wherein, when the uplink message is a normalreport message for report of the specific terminal device to network,the specific information is a terminal address included in the normalreport message.
 8. A network device in a network system including aplurality of network devices, the network device comprising: a receiver,implemented by a processor and including electrical circuits orintegrated circuits, configured to receive a response packet of aspecific downlink packet transmitted to a terminal device; a decisionunit, implemented by a processor and including electrical circuits orintegrated circuits, configured to analyze whether the response packetindicates the specific downlink packet is generated by a specificnetwork device among the plurality of network devices in the networksystem; and a routing unit, implemented by a processor and includingelectrical circuits or integrated circuits, configured to route theresponse packet to the specific network device when the specific networkdevice is a network device other than the network device receiving theresponse packet.
 9. The network device of claim 8, wherein the decisionunit is configured to detect a network device identifier included in atoken-related field within the response packet and decide a networkdevice having the detected network device identifier as the specificnetwork device.
 10. The network device of claim 8, wherein the decisionunit is configured to detect a second token value mapped to a firsttoken value of the token-related field within the response packetthrough a pre-stored token table and decide a network device allocatingthe second token value as the specific network device.
 11. The networkdevice of claim 10, further comprising a table generator configured to,when a downlink packet including the second token value is received fromthe specific network device, generate the token table by allocating thefirst token value different from the second token value.
 12. A method ofoperating a network device in a network system including a plurality ofnetwork devices, the method comprising: receiving a response packet of aspecific downlink packet transmitted to a terminal device; analyzingwhether the response packet indicates the specific downlink packet isgenerated by a specific network device among the plurality of networkdevices in the network system; and routing the response packet to thespecific network device when the specific network device is a networkdevice other than the network device receiving the response packet. 13.The method of claim 12, wherein the deciding comprises detecting anetwork device identifier included in a token-related field within theresponse packet and deciding a network device having the detectednetwork device identifier as the specific network device.
 14. The methodof claim 12, wherein the deciding comprises detecting a second tokenvalue mapped to a first token value of the token-related field withinthe response packet through a pre-stored token table and deciding anetwork device allocating the second token value as the specific networkdevice.
 15. The method of claim 14, further comprising, generating thetoken table by allocating the first token value different from thesecond token value when a downlink packet including the second tokenvalue is received from the specific network device.